The Ad Hillary Made Without David Letterman's Permission

A clip of Trump on the 'Late Show' was used by the Clinton campaign sans approval of Letterman's Worldwide Pants company.

It has become one of Hillary Clinton's most effective attack ads: Donald Trump is shown boasting to David Letterman during a 2012 Late Show appearance that his top-selling neckties and shirts are made "somewhere" — until Letterman points out they're actually manufactured in China and Bangladesh.

Just one problem: the Clinton campaign never got permission from Letterman or his Worldwide Pants company to use the 25-second clip. Lawyers who consulted with THR are split on whether the use of the footage (owned by Worldwide Pants, not CBS) would be a "fair use," but the issue probably is moot: Letterman is a big Clinton supporter and likely would have given permission — if he had been asked. A rep for Letterman declined to comment.

This story first appeared in the Sept. 9 issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.